Long-term prospective epidemiologic studies on hypertensive and atherosclerotic cardiovascular diseases, particularly coronary heart disease, are in progress, to elucidate key practical and theoretical questions left unclarified by studies to date. For this purpose, use is being made of data on two cohorts of men employed by the Chicago Peoples Gas Co. and one cohort of men employed by the Western Electric Co., plus data from the national cooperative Pooling Project and on almost 40,000 white and black men and women, chiefly 25-64 and identified in the Chicago Heart Association Detection Project in Industry from 1967 to 1973, being followed for 10 years to determine rates of mortality. The contribution of the following variables to risk of death both cause-specific and all causes, are being assessed by univariate and multivariate procedures for separate age-sex-race groups; plasma glucose level 1 hour after 50 gram oral load, history of diabetes mellitus, serum uric acid level, history of gout, obesity pure systolic hypertension, heart rate at rest, ECG abnormalities, the "classical" major risk factors (hypercholesterolemia, hypertension, cigarette smoking), nutritional and physical activity indices, alcohol and coffee consumption, and such demographic variables as nativity, education and marital status. For 4,108 persons, the contribution of scores from the Jenkins Activity Survey to risk of CHD death is being assessed.